Interface ObjectPool<T>

    • Method Summary

      All Methods Instance Methods Abstract Methods 
      Modifier and Type Method Description
      void addObject()
      Create an object using the factory or other implementation dependent mechanism, passivate it, and then place it in the idle object pool.
      T borrowObject()
      Obtains an instance from this pool.
      void clear()
      Clears any objects sitting idle in the pool, releasing any associated resources (optional operation).
      void close()
      Close this pool, and free any resources associated with it.
      int getNumActive()
      Return the number of instances currently borrowed from this pool.
      int getNumIdle()
      Return the number of instances currently idle in this pool.
      void invalidateObject​(T obj)
      Invalidates an object from the pool.
      void returnObject​(T obj)
      Return an instance to the pool.
    • Method Detail

      • returnObject

        void returnObject​(T obj)
                   throws java.lang.Exception
        Return an instance to the pool. By contract, obj must have been obtained using borrowObject() or a related method as defined in an implementation or sub-interface.
        Parameters:
        obj - a borrowed instance to be returned.
        Throws:
        java.lang.IllegalStateException - if an attempt is made to return an object to the pool that is in any state other than allocated (i.e. borrowed). Attempting to return an object more than once or attempting to return an object that was never borrowed from the pool will trigger this exception.
        java.lang.Exception - if an instance cannot be returned to the pool
      • invalidateObject

        void invalidateObject​(T obj)
                       throws java.lang.Exception
        Invalidates an object from the pool.

        By contract, obj must have been obtained using borrowObject() or a related method as defined in an implementation or sub-interface.

        This method should be used when an object that has been borrowed is determined (due to an exception or other problem) to be invalid.

        Parameters:
        obj - a borrowed instance to be disposed.
        Throws:
        java.lang.Exception - if the instance cannot be invalidated
      • addObject

        void addObject()
                throws java.lang.Exception,
                       java.lang.IllegalStateException,
                       java.lang.UnsupportedOperationException
        Create an object using the factory or other implementation dependent mechanism, passivate it, and then place it in the idle object pool. addObject is useful for "pre-loading" a pool with idle objects. (Optional operation).
        Throws:
        java.lang.Exception - when PooledObjectFactory.makeObject() fails.
        java.lang.IllegalStateException - after close() has been called on this pool.
        java.lang.UnsupportedOperationException - when this pool cannot add new idle objects.
      • getNumIdle

        int getNumIdle()
        Return the number of instances currently idle in this pool. This may be considered an approximation of the number of objects that can be borrowed without creating any new instances. Returns a negative value if this information is not available.
        Returns:
        the number of instances currently idle in this pool.
      • getNumActive

        int getNumActive()
        Return the number of instances currently borrowed from this pool. Returns a negative value if this information is not available.
        Returns:
        the number of instances currently borrowed from this pool.
      • clear

        void clear()
            throws java.lang.Exception,
                   java.lang.UnsupportedOperationException
        Clears any objects sitting idle in the pool, releasing any associated resources (optional operation). Idle objects cleared must be PooledObjectFactory.destroyObject(PooledObject).
        Throws:
        java.lang.UnsupportedOperationException - if this implementation does not support the operation
        java.lang.Exception - if the pool cannot be cleared
      • close

        void close()
        Close this pool, and free any resources associated with it.

        Calling addObject() or borrowObject() after invoking this method on a pool will cause them to throw an IllegalStateException.

        Implementations should silently fail if not all resources can be freed.